[iOS] (Grid) Virtualisation looks broken, content of rows/items is strangely "replaced" while scrolling.

[hannojg]

🐛 The Bug:

We are currently building a gallery based on RLV, thus we are rendering many images and run into strange issues on iOS. The bug is best described by having a look at this video:

https://user-images.githubusercontent.com/16821682/103177922-b2562000-487e-11eb-9dd5-c8911f9cc39c.mp4

As you can see the images content is strangely replaced while scrolling. In our production app, not using expo this is even worse.

👀 Observations:

• Only happens on iOS
• When setting a key prop to the most outer view of the rowRenderer's return value, the bug doesn't appear (but ofc it destroyed all of RLVs mechanisms, but maybe this gives a hint of whats happening).

Reproduction:

https://snack.expo.io/@hannojg/rlv-image-issue

[philly25]

Got the same, and the only workaroud I found is to set renderAheadOffset prop: renderAheadOffset={dimensions.height}